There are two trends in new printed circuit board (PCB) designs. The first trend is the result of a continuous need for circuitry miniaturization. It requires high concentration of small holes to provide interconnections between layers of multi-layer designs. Many of today's high-density PCBs use holes in the range of 200 to 350 Microns diameter. However, new designs require holes in a 50 to 250 Micron diameter range. New types of multi-layer designs are thin (4 to 8 layers) and small in size and are produced on large panels in step-and-repeat fashion. A key to efficiently producing these new types of boards is in the ability of stacking them high in production without drill breakage and degradation of accuracy.
The second trend is for utilization of large motherboards, characterized by a high layer count, up to 50 layers. The size of these motherboard panels is large and relatively thick, e.g. up to 15 mm for some exemplary applications. These motherboards present an additional challenge to the drilling process because of a very high diameter to depth aspect ratio and large volume of copper, which has to be removed from the hole.
Existing drilling machines were not suited for these types of tasks. The amplitude of machine vibration can be too large for a reliable, small deep hole drilling process. The drilling process has to be slowed down to avoid drill breakage and pecking has to be implemented in the case of high diameter to depth aspect ratio drilling. This situation erodes productivity of machines and increases costs of drilling.